Chiral Phase Change Nanomaterials

Abstract

Active chiral nanomaterials are dynamic photonic materials offering unprecedented opportunities for high-speed temporal control of chiral light-matter interactions. However, demonstrating dynamic solid-state chiral platforms remains challenging in the UV/VIS regime. By amalgamating the unique characteristics of geometric chirality and the non-volatile phase change phenomena, chiral phase change nanomaterials hold great promise for energy-efficient applications in reconfigurable optoelectronics, bio-photonics, and information storage technologies. In this work, we reveal a bottom-up, wafer-scale fabrication technique for (Formula presented.) (Formula presented.) (Formula presented.) (GST) with a high degree of nanoscale control in three spatial dimensions, yielding densely packed phase change nanomaterials featuring 15 nm cross-sectional diameters. We demonstrate tunable circular birefringence and dichorism, corroborated by a numerical model, explaining the origin of chiro-optical effects observed in the material plasmonic regime. Furthermore, the GST nano-helices exhibit over 50K reversible cycles using a repeated sequence of four 4 (Formula presented.) crystallization pulses and a singular 400 ns pulse for amorphization, enabling temporal manipulation of the chiro-optical response maximally at 410 nm. Our work not only achieves the critical goal of wafer-scale nano-engineering of chiral chalcogenide phase change materials but also reversible optical actuation with low programming fluence, long cycling endurance, and fast switching.